ACE4054 - ACE Technology Co., LTD.

ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Description
The ACE4054 is a single cell, fully integrated constant current (CC) / constant voltage (CV) Li-ion battery
charger. Its compact package with minimum external components requirement makes the ACE4054 ideal
for portable applications.
No external sense resistor or blocking diode is necessary for the ACE4054. Build-in thermal feedback
mechanism regulates the charge current to control the die temperature during high power operation or at
elevated ambient temperature.
The ACE4054 has a pre-charge function for trickle charging deeply discharged batteries. The fast
charge current can be programmed by an external resistor. CV regulation mode is automatically enabled
once the battery’s charging curve reaches the constant voltage portion. The output current then decays
and is finally terminated once the charge current drops to 1/10th of the programmed value. The ACE4054
keeps monitoring the battery voltage and enables a new charge cycle once the voltage drops by 150mV
below the CV value.
Power supply state is constantly monitored and the battery drain current is reduced to minimum value
automatically when the ACE4054 senses a lack of input power. In its shutdown mode, the ACE4054 can
reduce the supply current to less than 25μA. A status pin outputs a logic HIGH/LOW to indicate the
charging status and the presence of power supply.
Other features include charge current monitor, under-voltage lockout.
Features
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Standalone Capability with no Requirement of External MOSFET, Sense Resistor or Blocking Diode
Complete Linear Charger in Compact Package for Single Cell Lithium-Ion Batteries
Programmable Pre-charge, Fast Charge and Termination Current
Constant-Current/Constant-Voltage Operation with Thermal Regulation to Maximize Charge Rate
Without Risk of Overheating
Charges Single Cell Li-Ion Batteries Directly from USB Port
Preset 4.2V Charge Voltage with ±1% Accuracy
Automatic Recharge
Charge Status Output Pin
C/10 Charge Termination
25μA Supply Current in Shutdown
2.9V Trickle Charge Threshold
Soft-Start Limits Inrush Current
Available in 5-Lead SOT-23 (0.5A) and ESOP-8 Package (1A)
Application
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Cellular Telephones,PDAs,MP3 Players
Charging Docks and Cradles
Bluetooth Applications
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Absolute Maximum Ratings
Parameter
Max
Unit
VCC
-0.3 ~6.5
V
PROG
-0.3 ~ VCC+0.3 V
BAT
CHRG
BAT Short-Circuit Duration
-0.3 ~ 5
V
-0.3 ~ 6.5
V
Continuous
PROG Pin Current
600
μA
Maximum Junction Temperature
125
℃
Operating Ambient Temperature Range
-40 ~ 85
℃
Storage Temperature Range
-40 ~ 125
℃
Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability.
Packaging Type
SOT-23-5
5
1
ESOP-8
4
2
1
8
2
7
3
6
4
5
3
Description SOT-23-5 Description ESOP-8
CHRG
GND
1
NC
1.8
2
PROG
2
BAT
3
GND
3
VCC
4
VCC
4
PROG
5
BAT
5
NC
6
CHRG
NC
7
8
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Pin Description
CHRG (Pin 1):Open-Drain Charge Status Output. The CHRG pin outputs low when the battery is charging.
When the ACE4054 detects an under voltage lockout condition, CHRG is forced high
impedance.
GAN (Pin 2):Ground.
BAT (Pin 3):Charge Current Output. This pin provides charge current to the battery and regulates the final
float voltage to 4.2V which is set by an internal precision resistor divider.
VCC (Pin 4):Positive Input Supply. Needs to be bypassed with at least a 1μF capacitor. When input
voltage drops to within 30mV of the BAT pin voltage, the ACE4054 switches to shutdown
mode.
PROG (Pin 5):Program, Monitor the charge current and Shutdown. This pin set to 1V in constant-current
mode. The charge current is programmed by connecting a 1% resistor, RPROG, to GND
pin. The charge current can be calculated using the following formula:
I BAT = ( VPROG / RPROG) ∙ 1000
The PROG pin can also be used to switch the charger to shutdown mode by disconnecting the program
resistor from ground. This results in a 3μA current to pull the PROG pin to a high level shutdown threshold
voltage, thus stop the charging and reduce the supply current to 25μA. This pin is also clamped to
approximately 2.4V. A higher voltage beyond this value will draw currents as high as 1.5mA. Device
normal operation can be resumed by reconnecting the RPROG resistor to ground.
Ordering information
ACE4054 XX +
H
Halogen - free
Pb - free
BN : SOT-23-5
IM : ESOP-8
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Block Diagram
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Electrical Characteristics
VCC=5V,TA=25℃, RPROG=10K, unless otherwise note.
Parameter
Symbol
Input Supply Voltage
VCC
Input Supply Current
Regulated Output (Float)
Voltage
BAT Pin Current
Trickle Charge Current
Trickle Charge Threshold
Voltage
Trickle Charge Hysteresis
Voltage
VCC Undervoltage Lockout
Threshold
VCC Undervoltage Lockout
Hysteresis
ICC
VFLOAT
Min
Typ
Max
Units
6.0
V
300
2000
μA
200
500
μA
25
50
μA
4.25
Charge Mode(Note 1)
Standby Mode (Charge
Terminated)
Shutdown Mode (RPROG Not
Connected, VCC<VBAT, or
VCC<VULO)
IBAT=40mA
4.158
4.2
4.242
V
Current Mode
93
100
107
mA
RPROG=2K, Current Mode
465
500
535
mA
Standby Mode, VBAT=4.2V
Shutdown Mode (RPROG Not
Connected)
Sleep Mode, VCC=0V
0
-2.5
-6
μA
1
5
μA
1
5
μA
ITRIKL
VBAT<VTRIKL, RPROG=2K
20
45
70
mA
VTRIKL
VBAT Rising
2.8
2.9
3
V
60
80
110
mV
3.7
3.8
3.92
V
150
200
300
mV
PROG Pin Rising
1.15
1.21
1.30
V
PROG Pin Falling
0.9
1
1.1
V
VCC from Low to High
70
100
140
mV
VCC from High to Low
5
30
50
mV
ITERM
Note 3
0.085
0.1
0.115
mA
VPROG
VCHRG
Current Mode, VBAT=4V
ICHRG=5mA
0.93
1
1.07
V
0.35
0.6
V
VRECHRG
VFLOAT-VRECHRG
100
150
200
mV
IBAT
VTRHYS
VUV
From VCC Low to High
VUVHYS
Manual Shutdown
Threshold Voltage
VMSD
VCC-VBAT Lockout
Threshold Voltage
VASD
C/10 Termination Current
Threshold
PROG Pin Voltage
CHRG Pin Output Low
Voltage
Recharge BAT Threshold
Voltge
Junction Temperature in
Constant Temperature
Mode
Conditions
TLIM
℃
120
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ACE4054
Fully integrated constant current/constant voltage
Power FET “ON”
Resistance (Between VCC
and BAT)
Soft-Start Time
Recharge Comparator
Filter Time
Termination Comparator
Filter Time
PROG Pin Pull-Up Current
Li-ion battery charger
RON
0.25
Ω
100
μs
Tss
IBAT=0 to IBAT=100V/RPROG
tRECHARGE
VBAT High to Low
0.5
5
20
Ms
tTERM
IBAT Falling Below ICHG/10
400
1000
2500
μs
IPROG
μA
3
Note :
1.
Supply current includes PROG pin current (approximately 100μA) but does not include any current delivered to the battery
through the BAT pin (approximately 100mA)
2.
ITREM is expressed as a fraction of measured full charge current with indicated PROG resistor
Application Circuit
CHRG
Supply
Voltage
BAT
VCC
PROG
ACE4054
GND
4.2V Li-Ion
Battery
On/Off
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ACE4054
Fully integrated constant current/constant voltage
Typical Characteristic
Li-ion battery charger
VCC=5V,TA=25℃, unless otherwise noted
Charge Current vs Battery Voltage
(VCC=4.5V)
VBAT (V)
Charge Current vs PROG Pin Voltage
VPROG (V)
Charge Current vs Supply Voltage
(Vbat=4.0V)
VCC (V)
Regulated Voltage vs Supply Voltage
VCC (V)
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ACE4054
Fully integrated constant current/constant voltage
PROG Pin Current vs PROG Pin Voltage
(Pul-Up Current)
VPROG (V)
CHRG Pin Current vs CHRG Pin Voltage
(Strong Pull Down State)
VCHRG (V)
Regulated Voltage vs Temperature
T (℃)
Li-ion battery charger
PROG Pin Current vs PROG Pin Voltage
(Clamp Current)
VPROG (V)
CHRG Pin Current vs CHRG Pin Voltage
(Weak Pull Down State)
VCHRG (V)
PROG Pin Voltage vs Temperature
T (℃)
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ACE4054
Fully integrated constant current/constant voltage
Recharge Voltage vs Temperature
T (℃)
Li-ion battery charger
Trickle Charge Voltage vs Temperature
T (℃)
Detailed description
The ACE4054 is a single cell, fully integrated constant current (CC) / constant voltage (CV) Li-ion battery
charger. It can deliver up to 600mA of charge current with a final float voltage accuracy of ±1%. The
ACE4054 has a build-in thermal regulation circuitry that ensures its safe operation. No blocking diode or
external current sense resistor is required; hence reduce the external components for a basic charger
circuit to two. The ACE4054 is also capable of operating from a USB power source.
Normal Charge Cycle
The ACE4054 initiates a charge cycle once the voltage at the VCC pin rises above the UVLO threshold
level. A ±1% precision resistor needs to be connected from the PROG pin to ground. If the voltage at the
BAT pin is less than 2.9V, the charger enters trickle charge mode. In this mode, the charge current is
reduced to nearly 1/10 the programmed value until the battery voltage is raised to a safe level for full
current charging.
The charger switches to constant-current mode as the BAT pin voltage rises above 2.9V, the charge
current is thus resumed to full programmed value. When the final float voltage (4.2V) is reached the
ACE4054 enters constant-voltage mode and the charge current begins to decrease until it drops to 1/10
of the preset value and ends the charge cycle.
Programming Charge Current
The charge current is programmable by setting the value of a precision resistor connected from the
PROG pin to ground. The charge current is 1000 times of the current out of the PROG pin. The program
resistor and the charge current are calculated using the following equations:
The charge current out of the BAT pin can be determined at any time by monitoring the PROG pin
voltage using the following equation:
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
ACE4054 has a self temperature limiting (STL) function, the chip starts to limit its charge current by
reducing VPROG gradually after silicon temperature rises above 70℃. Say if the difference of junction
and ambient temperature is 45℃ at certain power rating, ACE4054 would have the same charge current
and junction temperature as chips without STL function at room temperature. As the ambient temperature
rises up to 55℃, a chip without STL would have 100℃ of junction temperature, while ACE4054 would
reduce its charge current and hence the junction temperature would be much lower. The STL function
helps to improve system reliability.
Charge Termination
The ACE4054 keeps monitoring the PROG pin during the charging process. It terminates the charge
cycle when the charge current falls to 1/10th the programmed value after the final float voltage is reached.
When the PROG pin voltage falls below 100mV for longer than tTERM (typically 1ms), charging is
terminated. The charge current is latched off and the ACE4054 enters standby mode, where the input
supply current drops to 200μA. (Note: C/10 termination is disabled in trickle charging and thermal limiting
modes).
During charging, the transient response of the circuit can cause the PROG pin to fall below 100mV
temporarily before the battery is fully charged, thus can cause a premature termination of the charge
cycle. A 1ms filter time (tTERM) on the termination comparator can prevent this from happening. Once the
average charge current drops below 1/10th the programmed value, the ACE4054 terminates the charge
cycle and ceases to provide any current through the BAT pin. In this state, all loads on the BAT pin must
be supplied by the battery.
Figure 1. Charge Cycle Diagram
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
The ACE4054 constantly monitors the BAT pin voltage in standby mode and resume another charge
cycle if this voltage drops below the recharge threshold (VRECHRG). User can also manually restart a
charge cycle in standby mode either by removing and then reapplied the input voltage or restart the
charger using the PROG pin. A diagram of typical charge cycle is shown in figure 1.
Charge Status Indicator (CHRG)
There are two different states of the charge status output, namely strong pull-down (~10mA) and high
impedance. The strong pull-down state indicates that the ACE4054 is in a charge cycle. When the charge
cycle has terminated, the pin state is then determined by undervoltage lockout conditions. If the difference
between Vcc and BAT pin voltage is less than 100mV or insufficient voltage is applied to the VCC pin,
High impedance appears on the charge statues pin.
Thermal Limiting
Build-in feedback circuitry mechanism can reduce the value of the programmed charge current once the
die temperature tends to rise above 120℃, hence prevents the temperature from further increase and
ensure device safe operation.
Undervoltage Lockout (UVLO)
Build-in undervoltage lockout circuit monitors the input voltage and keeps the charger in shutdown mode
until VCC rises above the shutdown mode until VCC rises above the undervoltage lockout threshold. The
UVLO circuit has a built-in hysteresis of 200mV. Furthermore, to protect against reverse current in the
power MOSFET, the UVLO circuit keeps the charger in shutdown mode if VCC falls to within 30mV of the
battery voltage. If the UVLO comparator is tripped, the charger will not come out of shutdown mode until
VCC rises 100mV above the battery voltage.
Manual Shutdown
Floating the PROG pin by removing the resistor from PROG pin to ground can put the device in
shutdown mode. The battery drain current is thus reduced to less than 5μA and the supply current to less
than 50μA. Reconnecting the resistor back will restart a new charge cycle.
The CHRG pin is in a high impedance state if the ACE4054 is in undervoltage lockout mode.
Automatic Recharge
After the termination of the charge cycle, the ACE4054 constantly monitors the BAT pin voltage and
starts a new charge cycle when the battery voltage falls below 4.05V, keeping the battery at fully charged
condition. CHRG output enters a strong pull-down state during recharge cycles.
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Applications information
Stability Considerations
When a battery is connected to the output, the constant-voltage mode feedback is always stable.
However, in the case of absence of battery, an output capacitor is recommended to reduce ripple voltage.
In the case of high value capacitance or low ESR ceramic capacitors, a small value series resistor (~1Ω)
is recommended. No series resistor is needed if tantalum capacitors are used.
In constant-current mode, the PROG pin is in the feedback loop, thus its impedance affects the stability.
The maximum allowed value of the program resistor is 20K, and additional capacitance reduces this value.
The pole frequency at the PROG pin needs to be kept above 100kHz to maintain device stability.
Therefore, the maximum resistance value can be calculated from the following equation, CPROG is the
capacitance loaded to the PROG pin.
Average rather than instantaneous charge current is more of a concern. A simple low pass filter can be
used on the PROG pin to measure the average battery current as shown in Figure 2. A 10K resistor has
been added between the PROG pin and the filter capacitor to ensure stability.
ACE4054
Figure 2. Isolating Capacitive Load PROG Pin and Filtering
Power Dissipation
The power dissipated in the IC causes the rise of die temperature. Most of the power dissipation is
caused by the internal power MOSFET, and can be calculated by the following equation:
PD= (VCC – VBAT) ∙ IBAT
Where PD is the power dissipated, VCC is the input supply voltage, VBAT is the battery voltage and
IBAT is the charge current. The approximate ambient temperature at which the thermal feedback begins
to protect the IC is:
TA = 120℃ - PDθJA
TA = 120℃ - (VCC – VBAT) ∙ IBAT ∙ θJA
Example: An ACE4054 operating from a 5V USB supply is programmed to supply 400mA full-scale
current to a discharged Li-Ion battery with a voltage of 3.75V. Assuming ΘJA is 150℃ / W (see Board
Layout Considerations), the ambient temperature at which the ACE4054 will begin to reduce the charge
current is approximately:
TA = 120℃ - (5V – 3.75V) ∙ (400mA) ∙ 150℃ / W
TA = 120℃ -0.5W ∙ 150℃ / W = 120℃ - 75℃
TA = 45℃
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
The ACE4054 can be used above 45℃ ambient, but the charge current will be reduced from 400mA.
The approximate current at a given ambient temperature can be approximated by:
Using the previous example with an ambient temperature of 60℃, the charge current will be reduced to
approximately:
Moreover, when thermal feedback reduces the charge current, the voltage at the PROG pin is also
reduced proportionally as discussed in the operation section.
It is important to remember that ACE4054 applications do not need to be designed for worst-case
thermal conditions sine the IC will automatically reduce power dissipation when the junction temperature
reached approximately 120℃.
Thermal Considerations
Due to its compact size, it is of great importance to use a good thermal PC board. Good thermal
conduction increases maximum allowed charge current value.
The thermal path for the heat generated by the IC is from the die to the copper lead frame, through the
package leads, (especially the ground lead) to the PC board copper. The PC board copper is the heat
sink. The footprint copper pads should be as wide as possible and expand out to larger copper areas to
spread and dissipate the heat to the surrounding ambient. Feedthrough vias to inner or backside copper
layers are also useful in improving the overall thermal performance of the charger. Other heat sources on
the board, not related to the charger, must also be considered when designing a PC board layout
because they will affect overall temperature rise and the maximum charge current.
Increasing Thermal Regulation Current
Reducing the voltage drop across the internal MOSFET can significantly decrease the power dissipation
in the IC. Minimized power dissipation results in reduced die temperature rise and hence equivalent
increased charge current in thermal regulation. One way is to bypass some of the current through an
external component, such as a resistor or diode.
Example: An ACE4054 operating from a 5V wall adapter is programmed to supply 600mA full-scale
current to discharged Li-Ion battery with a voltage of 3.75V. Assuming θJA is 125℃ / W, the approximate
charge current at an ambient temperature of 25℃ is:
By dropping voltage across a resistor in series with a 5V wall adapter (shown in Figure 3), the on-chip
power dissipation can be decreased, thus increasing the thermally regulated charge current
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
ACE4054
Figure 3. A Circuit to Maximize Thermal Mode Charge Current
VCC Bypass Capacitor
Due to their self-resonant and high Q characteristics, some types of ceramic capacitors can cause high
voltage transients under some start-up conditions (i.e connecting the charger input to a live power source).
Adding a small value resistor in series with the ceramic capacitor can minimize start-up voltage transients.
CHARGE Current Soft-Start
To avoid the start-up transients, a soft-start circuit is included to ramp the charge current from zero to
programmed value over a period of time. This has the effect of minimizing the transient current load on
the power supply during start-up.
CHRG Status Output Pin
When the input voltage is larger than the undervoltage lockout threshold, a pull-down current of 20μA to
the pin indicates that the device is ready to charge. When a discharged battery is connected to the
charger, the constant current portion of the charge cycle begins and the CHRG pin is pulled to ground.
The CHRG pin can sink up to 10mA to drive an LED that indicates that a charge cycle is in progress.
When the battery is close to fully charged, the charger switches to the constant-voltage portion of the
charge cycle and the charge current begins to drop. When the charge current drops below 1/10 of the
programmed current, the charge cycle ends and the strong pull-down is replaced by the 20μA pull-down
as mentioned before, indicating that the charge cycle has ended.
If the input voltage is removed or drops below the undervoltage lockout threshold, the CHRG pin
becomes high impedance. Figure 4 shows that by using two different value pull-up resistors, a
microprocessor can detect all three states from this pin.
ACE4054
Figure 4. Using a Microprocessor to Determine CHRG State.
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
To detect the charge statues of the ACE4054, connect a microprocessor and force the digital output pin
(OUT) high and measure the voltage at the CHRG pin, as shown in Figure4.
The N-channel MOSFET will pull the pin voltage low even with the 2K pull-up resistor. Once the charge
cycle terminates, the N-channel MOSFET is turned off and a 20μA current source is connected to the
CHRG pin. The IN pin will then be pulled high by the 2K pull-up resistor. When the CHRG is high
impedance, the IN pin will be pulled high, indicating that the part is in a UVLO state.
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Packing Information
SOT-23-5
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Packing Information
ESOP-8
HEAT SLUG
(BTM)
NOTES: ALL DIMENSIONS REFER TO JEDEC STANDARD MS-012 AA DO NOT INCLUDE MOLD
FLASH OR PROTRUSIONS.
BASE METAL
SECTION B-B
VER 1.6
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ACE4054
Fully integrated constant current/constant voltage
Li-ion battery charger
Notes
ACE does not assume any responsibility for use as critical components in life support devices or systems
without the express written approval of the president and general counsel of ACE Electronics Co., LTD.
As sued herein:
1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant
into the body, or (b) support or sustain life, and shoes failure to perform when properly used in
accordance with instructions for use provided in the labeling, can be reasonably expected to result in
a significant injury to the user.
2. A critical component is any component of a life support device or system whose failure to perform can
be reasonably expected to cause the failure of the life support device or system, or to affect its safety
or effectiveness.
ACE Technology Co., LTD.
http://www.ace-ele.com/
VER 1.6
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